In cooperative wireless networks, virtual antenna arrays formed by distributed network nodes can provide cooperative diversity. Obviating channel estimation, differential schemes have long been appreciated in conventional multi-input multi-output (MTMO) communications. However, distributed differential schemes for general cooperative network setups have not been thoroughly investigated. In this paper, we develop and analyze two distributed differential schemes using both decode-and-forward (DF) and amplify-and-forward (AF) relaying protocols. For each scheme and relaying protocol combination, we derive the optimum maximum likelihood (ML) decision rule and its low-complexity suboptimum alternative. Simulations confirm that both schemes provide full diversity gain with either DF or AF relaying protocols. In addition, we carry out performance and rate comparisons between the two distributed differential schemes and preliminary investigations on the optimal relay positioning for the DF and AF relaying protocols.